摘要:

AbstractThe amino‐ and carboxyl‐terminal amino acids of proteolipids from neural and non‐neural sources were investigated. Amino‐terminal amino acids were identified and quantitated by the dansyiation procedure. Carboxyl‐terminal amino acids were determined after hydrazinolysis or enzymatic hydrolysis with carboxypeptidases. Proteolipid from white matter showed two terminal amino acids, regardless of the method of preparation. The major N‐terminal amino acid was glycine and the minor one was glutamic acid or glutamine. The corresponding C‐terminal amino acids were phenylalanine and glycine. Preparations of white matter proteolipid, therefore, contained more than one protein or protein chain. Proteolipids from brain mitochondria, heart, liver and kidney were characterized by N‐terminal aspartic acid or asparagine and C‐terminal lysine residues and they exhibited an amino acid composition which differed from white matter proteolipid. Our results suggest the existence of two classes of proteolipids, a myelin type and a non‐myelin type. Synaptic membrane and grey matter proteolipids exhibited characterist

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1973.tb00242.x

出版商:Blackwell Publishing Ltd    

年代:1973

数据来源: WILEY

摘要:

AbstractAn assay has ken developed for total sulphur which is based on a wet oxidation and measurement with a spectrophotofluorometer of light scattering by barium sulphate. The method has been adapted to the measurement of isethionate in squid nerve and blood, in other cephalopod nerve, and in the nerve tissue of other species including mammals. A correlation has been found between isethionate contents and the activity in the same tissues of one kind of DFP‐hydrolysing enzyme, the highest levels of both being in squid nerve. Squid nerve also took up cysteine rapidly and metabolized it predominantly to hypotaurine but not to isethionate. We speculate that a hypotaurine derivative is a reserve form of isethionate, and that the so‐called DFPase is involved in the release of hypotaurine and its metabolism to isethionate as nee

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1973.tb00243.x

出版商:Blackwell Publishing Ltd    

年代:1973

数据来源: WILEY

摘要:

AbstractThe activity of tryptophan hydroxylase (EC 1.99.1.4) in the region of the raphé nuclei of rat brain was higher than that of any other brain area. The content of serotonin and the rate of serotonin synthesis were also highest in the raphé nuclei. Following the administration ofp‐chlorophenylalanine the injection of tryptophan and pargyline increased the content of serotonin in the region of the raphé nuclei of rat brain. The results suggest that the raphé nuclei retained the capacity to hydroxyl‐late tryptophan to some extent after the injection ofp‐chlorophen

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1973.tb00244.x

出版商:Blackwell Publishing Ltd    

年代:1973

数据来源: WILEY

摘要:

AbstractBy macroautoradiography and by GLC separation, differences in the uptake of radioactive carbon from [U‐14C]glucose into free amino acids (glutamate + glutamine, aspartate + asparagine, GABA, alanine and glycine) in mouse cerebral neocortex, hippocampus, thalamus and hypothalamus were investigated.(1) The autoradiographical densities in the thalamus, cerebral neocortex and hippocampus measured with a microdensitometer were higher than that in the hypothalamus at 5 min after subcutaneous injection. At 180 min, densities in the cerebral neocortex, hippocampus and hypothalamus were higher than that in thalamus.(2) The free amino acid levels determined by GLC varied with each brain region.(3) The specific radioactivity (d.p.m./μmol) of alanine in each brain region was higher than that of the other amino acids at 5 min after the injection. The specific radioactivity of GABA in the brain regions was clearly higher than that of (glutamate + glutamine), (aspartate + asparagine) and glycine at 5 and 15 min.(4) The autoradiographical data were in good agreement with the chemical data at 5 min but were different at 180 min.(5) Variations in specific radioactivity of each free amino acid among brain regions at 5 min were influenced greatly by existing free amino acid concentrations in each regi

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1973.tb00245.x

出版商:Blackwell Publishing Ltd    

年代:1973

数据来源: WILEY

摘要:

Abstract6‐Hydroxydopamine and its correspondingortho‐ andpara‐quinones were injected intraperitoneally into male Swiss‐Webster mice. Measurements made 72 h after injection showed that all three compounds caused a decrease in the uptake of [3H]norepinephrine into slices of mouse heart tissuein vitro, a decrease in the endogenous content of heart norepine‐phrine, and a disappearance of the adrenergic nerve plexus of the mouse iris as viewed by fluorescence histochemistry. These data suggest that both theortho‐ andpara‐quinones of 6‐hydroxydopamine are capable of producing a chemical sympathectomy similar to that caused by 6

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1973.tb00246.x

出版商:Blackwell Publishing Ltd    

年代:1973

数据来源: WILEY

摘要:

AbstractCholine acetyltransferase from rat brain is present in three different molecular forms with isoelectric points at pH 7·4‐7.6, 7·7‐7·9 and 8·3. The three forms were identified in a highly purified enzyme preparation, in a preparation of synaptosomes and in a cyto‐plasmic preparation from disrupted axons and perikarya (fraction S3). The three molecular forms differed in their affinities for synaptosome membranes and for a cation exchange resin (CM‐Sephadex C‐50). The positive surface charges of the different molecular forms and their affinities for membranes correlated well with their isoelectric points. The molecular form with jsoelectric point 8·3 had the largest positive surface charge and the highest membrane affinity. On isoelectric focusing of an extract from rat brain synaptosomes, the molecular form with isoelectric point 8·3 formed a complex with a negatively charged compound, presumably a protein. A method was developed to remove this compound by treatment with DEAE‐Sephadex or by precipitation with vinblastine. These procedures are similar to methods known to remove the neurotubular protein. The complex formation did not occ

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1973.tb00247.x

出版商:Blackwell Publishing Ltd    

年代:1973

数据来源: WILEY

摘要:

AbstractThe rates of accumulation of the catecholamine synthesizing and metabolizing enzymes proximal to a ligation on the sciatic nerve of the rat were studied. Dopamine‐β hydroxylase (EC 1.14.2.1) and tyrosine hydroxylase (EC 1.14.3a) accumulated at a similar rapid rate, and catechol‐O‐methyl‐transferase (EC 2.1.1.6), choline acetyltransferase (EC 2.3.1.6) and monoamine oxidase (EC 1.4.3.4) accumulated at the same slow rate, whereas DOPA decarboxylase (EC 4.1.1.26) accumulated at an intermediate rate. Based on clearance of the rapidly accumulating enzymes, absolute flow rates were estimated to be: 106‐167 mm/24 h for tyrosine hydroxylase; 138‐185 mm/24 h for dopamine‐β‐hydroxylase; and 36‐86 mm/24 h for DOPA decarboxylase. In contrast, the mean rate of transport of the slowly accumulating enzymes (monomine oxidase, catechol‐O‐methyltransferase and choline acetyltransferase) was approximately 3 mm/24 h. Colchicine and vinblastine completely blocked the axonal transport of both the rapidly and slowly transported enzymes. Studies of the subcellular distribution of each enzyme failed to confirm the suggestion that particulate enzymes are transported rapidly and soluble enzymes slowly. Our results suggest that the transport and inactivation of dopamine‐β‐hydroxylase, DOPA decarboxylase, and tyrosine hydroxylase are under different controls than monoamine oxidase and

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1973.tb00248.x

出版商:Blackwell Publishing Ltd    

年代:1973

数据来源: WILEY

摘要:

AbstractAdenosylmethionine decarboxylase from rat brain has been found to be similar to the same enzyme isolated from other rat tissues in regard to kinetic parameters, pH optimum, putrescine requirement, and subcellular location. Evidence is presented that pyridoxal phosphate is not the functional cofactor in enzymatic decarboxylation by the rat brain preparation. The capacity for spermidine synthesis in developing rat brain was determined by measurement of the activity of adenosylmethionine decarboxylase. The activity increased dramatically after 10 days of postnatal age. This increase occurred after the period of maximum nucleic acid synthesis, an observation which suggests that spermidine may have a role in the functional development of the brain.

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1973.tb00249.x

出版商:Blackwell Publishing Ltd    

年代:1973

数据来源: WILEY

摘要:

AbstractThe isolation of synaptic vesicles from mouse brain by a modification of previously reported methodology is described. Homogeneity of the preparations was ascertained by electron microscopy. Vesicles thus isolated contained cyclic AMP (365 ± 44 pmol/mg of protein; mean ± S.E.M.) and adenosine 3′,5′‐monophosphate phosphodiesterase activity (500 pmol/mg of protein per 30 min). The number of vesicles in three of the vesicle preparations was determined by a visual count of grid fields under the electron microscope. The content of cyclic AMP in the vesicles was calculated at 5000‐7500 molecules/vesiclc. The presence of cyclic AMP in the synaptic vesicles from presynaptic nerve endings would support a role for this nucleotide in nerve tra

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1973.tb00250.x

出版商:Blackwell Publishing Ltd    

年代:1973

数据来源: WILEY

摘要:

AbstractThe use of the glutamate dehydrogenase (EC 1.4.1.3) and β‐hydroxybutyrate dehydrogenase (EC 1.1.1.30) reactions for the calculation of the mitochondrial redox state of brain has been examined. To prevent post‐mortem anoxic metabolism, brains were frozen in less than a second by using a new technique. Levels of ketone bodies in brain were so low relative to the contamination by blood and extracellular fluid that calculation of the mitochondrial redox state using the β‐hydroxybutyrate dehydrogenase reaction was not practical. The concentrations of the non‐nucleotide substrates of the glutamate dehydrogenase reaction could be accurately measured in brain and themitochondrial [NAD+]/[NADH]ratio calculated from the ratio [α‐oxoglutarate] [NH4+]/[glutamate]. The calculation is valid if the ratio [α‐oxoglutarate] [NH4+]/[glutamate]in mitochondria is the same as that measured in whole tissue. The evidence supporting this conclusion is the near‐equilibrium of the aspartate aminotransferase (EC 2.6.1.l) reaction in brain and the observation by others that the distribution of label between α‐oxoglutarate and glutamate in brain, after administration of labelled precursors, conforms to expectation. The alanine aminotransferase (EC 2.6.1.2) reaction was not near equilibrium in brain, probably because of the lowin vivoac

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1973.tb00251.x

出版商:Blackwell Publishing Ltd    

年代:1973

数据来源: WILEY